Co-metabolic degradation activities of trichloroethylene by phenol-grown aerobic granules

Aerobic granule, a novel form of microbial aggregation, was explored for its potential in a co-metabolic degradation process using trichloroethylene (TCE) as the model compound and phenol as the primary substrate. Granulation process was conducted with phenol as the sole carbon and energy source, and phenol-acclimated sludge as seed sludge. TCE and phenol degradation activity of the biomass was monitored during granulation, together with other sludge characteristics. The biomass’ settling ability improved significantly with granulation, and the mean size increased from 100 to 600 μm. The biomass showed efficient and robust TCE co-metabolism activity, but the phenol-dependent specific oxygen utilization rate (SOUR), TCE instant transformation rate (Tr) and ultimate transformation capacity (TC) all exhibited decreasing trends during granulation. Compared to the seed sludge, stable granules retained most of the SOUR and Tr, but lost half of the original TC. Phenol and TCE degradation kinetic parameters of the granules were determined to be Vmax 1.59 mg g SS−1 min−1, KS 37.2 mg L−1, KI 461.8 mg L−1 for phenol; and Vmax 0.0142 mg g SS−1 min−1, KS 1.02 mg L−1 for TCE. 2.5 mol Cl− was released per mol TCE transformed, and the TC was approximately 0.011 g TCE g granule−1.

► Aerobic granule was explored for its potential in trichloroethylene co-metabolism.
► Phenol-grown aerobic granules showed high phenol and TCE degradation activities.
► Mature granule had lower removal rate and high affinity for phenol and TCE.
► Mature granule showed resilience in TCE removal and good tolerance to its toxicity.
► Nearly total TCE mineralization could be achieved by phenol-grown aerobic granules.